Norcold General Installation Instructions Introduction The following are general instructions for the installation of the ARP control. The refrigerator used as an example is a Norcold N641.3. Most of the Norcold units of this vintage are similar; your installation may differ from the following instructions. If you do not feel qualified, please seek the help of a technician who is skilled with automotive electrical wiring and knowledgeable regarding RV refrigeration. WARNING: The comments/instructions that follow this identifier are general suggestions for safety. It is up to the installer's discretion as to the method of installation. Remember, safety is the installer's first priority. These instructions are general comments to aid the installer. We can not impart fully adequate safety instructions because safety is the installer's responsibility which includes knowledge, skill, and abilities too vast to cover in this document. OPTIONAL: The comments/instructions that follow this identifier can be skipped if the installer has experience with the unit that they are doing the installation on. Once an installer has installed a number of ARP units, the procedure becomes obvious. Preparation of Manufacturers' Control for Wiring Fig. 1 -- Norcold Controller OPTIONAL Removal of Cover Referencing Fig. 1 for the following discussion: The cover to the Norcold control may optionally be removed so that the ARP control can be installed. It is best to know what the screws that hold the control to the cover may interfere with under the cover. With this particular control, there is about 1/4" clearance between all electrical components within the Norcold control, and its cover in the location where we are 1 of 12
recommending the install of the ARP control. In addition, one may splice the wire seen in Fig. 2 if so desired, rather than opening the cover, more on this later in the instructions. 1. Please take note to Norcold's safety instructions identified by the #1 in Fig. 1. WARNING: Please either copy or move the decal to another location so that a user can still access this safety information. 2. In order to remove the manufacturers' control cover, the wiring to the control must be removed. Disconnect the power supply to the refrigerator. Please take note that this control has the wires and their function identified on the yellow tag. One may use a paint pen, or tape and a marker to identify the position of the wires for reinstallation at a later time. Please consult your RV Wiring Instructions to find the proper location to disconnect the power to your refrigerator. 3. Remove the two screws securing the cover. Referencing Fig. 2 for the following discussion: Fig. 2 -- Norcold Controller Cover Removed 4. On this Norcold control install, we moved the 120VAC heater wire by disconnecting it from the control, then un-wrapping the wire which was looped around the lower absorber coil tube (#5). The 120VAC heater wire interferes with the ARP control if it is looped around the absorber coil as was done at the Norcold factory; your Installation may differ. The routing seen in this photo is desirable. The objective is to keep the high voltage wires away from the ARP control so that they do not introduce electrical noise. 5. Location of the lower absorber coil. 2 of 12
6. The two wires that are routed to the thermal switch on the N641 boiler housing (Fig. 3) are shown here. As seen in the figure, the wire to the right sends 12VDC to the bi-metallic switch, the left wire is the signal return from the bi-metallic switch. The installer can discern which wire is the 12VDC wire by powering up the control and using a Volte meter to test which one has power on it. Otherwise, when cutting one of the wires, one end of the splice will measure 12VDC and the other will not. The 12VDC wire will be connected to relay terminal 30. Some 1200 series have a similar sensor installed; please see section Norcold 1200 Series below. One may either splice one of these wires as seen later in this document, or use a short jumper to connect the ARP control relay. 7. OPTIONAL: Please note that we used aluminum duct tape to secure the high voltage igniter wire to the back of the refrigerator. The high voltage igniter wire is seen connected in Fig. 1, upper wire identified #2, and Fig. 2 is also marked #2 to identify the termination of the wire on the igniter coil. WARNING: Do not turn on the power supply to the refrigerator until you first reconnect the igniter coil wire. The aluminum tape serves a number of purposes: (a) It protects the wire from abrasion by other parts. (b) It helps reduce electrical noise in the rest of you RVs equipment. (c) It helps keep UV from deteriorating the insulation. Referencing Fig. 3 for the following discussion: Fig. 3 -- Boiler Housing Bi-Metallic Switch 8. This figure shows the destination of the two wires seen in Fig. 2, #6. One of the wires going to this switch will either be removed and re-inserted on the relay. Or, one of these wires 3 of 12
can be cut, and either end of the cut can be connected to relay as seen in Fig. 5. Please see the ARP control Wiring Instructions for more information. ARP Housing Preparation Cooling Unit Compartment Because the ARP control housing is universal, the installer needs to drill the holes desired for their particular Installation. Referencing Fig. 4 for the following discussion: Fig. 4 -- Housing Drilling 9. This figure shows a typical installation within the cooling unit compartment. The yellow arrows show the 3 wiring access holes which also act as drain holes in the event water enters the housing. The holes may be drilled with a drill size from 0.222" to 0.234" (15/64"). Drill the outer holes between the outer wall and the circuit board standoff within the housing. Drill the holes near to the bottom of the housing so that the surface that holds the cover in place retains the maximum material when done. WARNING: We recommend that you place a shield over the vent to your refrigerator when you pressure wash your RV. One can wrap plastic around the access door if so desired. None of the components within the cooling unit compartment want to get wet. Not many electrical systems are happy having up to 100psi soapy water directed at them. ARP Housing Preparation RV Interior Install If the installer so desires, the above holes may be drilled in the housing for the wires to exit if the wires do not exit through the back of the control. Holes on the bottom of the control housing provide ventilation, but these holes are not necessary. We recommend whenever possible to drill the mounting holes and secure the housing where desired, then drill the hole 4 of 12
for the wires through the back of the control housing. This makes for a clean Installation where the wiring is out of site. OPTIONAL: The installer can use putty to plug the hole where the wires pass from the interior to the exterior of the RV. Optionally, if there is not ventilation from the rear, we recommend drilling small holes at the bottom for air circulation as seen in Fig. 4. ARP Control and Relay Mount Fig. 5 -- Controller Installed and Wiring Referencing Fig. 5 and the Wiring Instructions for the following discussion: 10. This identifies the power connections on the manufacturers' control. Please note that a paint pencil was used to mark (+) red and (-) green power leads. WARNING: Automotive wiring is fairly straight forward. One factor that is not apparent is grounding of the system. Because your vehicle uses the chassis as a ground conductor, many problems can arise. This document can not attempt to give directions for different RV manufacture wiring. Rather, we can recommend good practice. Use a long wire and an ohm meter to measure the resistance between your vehicle battery ground, and grounds in your RV, such as the ground for your refrigerator. High resistance can be an issue. We can not give you a specification as to what high resistance is because this value has many factors associated with it. But, remember that any circuit that has high resistance (R), and high current (I), will drew too much power (P). High resistance on a high current circuit results in heat, and may result in a fire if the conditions are correct. Handy formulas: V= IR and P= IV. OPTIONAL: The ARP control ground wire should be connected at the origin of the refrigerator ground whenever possible. The origin location may be on the chassis, see your RV wiring information for further details. Grounding at the origin may be difficult on some RV's. By grounding at the refrigerators ground origin, this will help eliminate surges in the ground circuit 5 of 12
that can result from your refrigerator turning on/off. Best wiring practice, always make multiple grounds at a single location to avoid ground loops. Ground loops are the enemy of digital circuits like the ARP control. If there are problems after instillation of the ARP control, always go back to the power supply first to see if there are grounding issues. This installation used the junction of the wire that plugs into the ground connector on the manufacturers' circuit board. You may note that in the figures of this document, I connected my power and ground at the #10 location. This practice is generally acceptable if your refrigerator is running on either gas or 120VAC because these modes of operation draw very little power. The positive power supply can be connected directly to almost any power supply that will provide power. 11. This identifies the wire that was spliced to install on the relay. Fig. 2, #6 shows the origin of these wires on the circuit board. Fig. 3, #8 shows the destination of the wires, the bimetallic switch. In this figure, #11 shows one of the wires after being cut and a female spade connector installed at either end of the cut wire so that it can be installed on the relay. The Norcold 1200 series is similar, see below for this type of installation. OPTIONAL: The bi-metallic switch was an attempt to prevent fires. It is clear that when a part (bi-metallic switch) that can have +/-20F error on a good day, tremendous drift with age, and is insulated from the heat source is used; it can not do a very good job even when new. The two wires seen in Fig. 6, 3, and 5 simply open a circuit on the manufacturers' control if the bimetallic switch opens due to overheating. The ARP relay - normally closed terminals are connected to this wire splice. When the ARP control senses excessive heat in the boiler, it activates the relay, thereby opening this circuit, and turning off the heat source to the boiler. If for some reason the ARP control is not turned on, the bi-metallic switch can still turn off the heat to your refrigerator. To test the function of this circuit, simply pull one of the wires off the bi-metallic switch seen in Fig. 3. The manufacturers' control will turn off the heaters on the cooling unit. Another method, use the ARP control relay test function, please see the ARP Control Operators Manual for more details. Overview of Manufacturers' Control and ARP Control 6 of 12
Fig. 6 -- Overview of ARP Installation Fig. 6 is an overview that shows the ARP control installed. This figure should help show how all the components are arranged for this particular installation. ARP Temperature Sensor Installation The objective of the following section is to inform the installer of the best possible method to attach the ARP temperature sensor. The physics of the measurement should help the installer understand the location and results of the ARP measurement. Fig. 7 -- ARP Temperature Sensor and Clip Referencing Fig. 7 for the following discussion: 7 of 12
12. Cylindrical temperature sensor and the lead wire. 13. Clip that attaches the temperature sensor 12 to the cooling unit boiler tube. 14. Lead wire end of temperature sensor and lead wire exiting the sensor. This wire shall be located so that the wire exits the sensor housing 12 so that the lead wire will not make contact with the cooling unit boiler tube. The wire shall face down so as to drain any water away from the sensor. The sensor can be installed with or without gluing the sensor 12 to the clip 13. If the install location is hard to get to, we recommend gluing the sensor in the following manner to ease the installation. Determine the direction the clip is to be placed around the boiler tube. We will provide recommendations in later versions of this manual. The direction that the clip faces is dependent upon where the flue tube is for you particular make and model of refrigerator. For the installation in this example, the flue tube is directly behind the cooling unit boiler tube, thus either direction that the clip is installed will work. Note that the clip is glued opposite to the direction seen in this photo in the following figures. Gluing Sensor to Clip Once the orientation of the sensor and clip are determined, put a few drops of Supper Glue Gel on the clip within the fastening channel. Press the sensor into the cannel so that the clip is about in the middle of the sensor housing. If a mistake is made, use acetone to remove the sensor from the clip. WARNING: Keep the Super Glue and solvents such as acetone away from the potting at the end of the sensor housing #14. The sensor is not designed to be submerged in liquids. OPTIONAL: If one wants to add a level of protection, high temperature sensor safe RTV silicone (Permatex Ultra Copper Item 81878) can be used as a glue to directly glue the sensor to the cooling unit boiler tube. The silicone can also help water proof the sensor by putting a bead around the end of the sensor #14. We have field tested the above recommended silicone product; we have sensors that have been in the field for over 4 years and without a problem when mounted in this manner. Kapton tape was used to secure the sensor to the boiler for gluing purposes. The sensor is easy to remove if this method is used. Further instructions may be provided upon request. 8 of 12
Fig. 8 -- Access to Sensor Installation Location Referencing Fig. 8 for the following discussion: WARNING: There are sharp objects within the cooling unit compartment. Sheet metal is very sharp at the edges. Please be mindful of sharp objects that may cut you. In addition, a respirator can be used to avoid breathing of the fiberglass dust. This example, the boiler housing is sheet metal. All of the refrigerators (Dometic or Norcold) that have sheet metal boiler housings use similar methods to gain access to the heater elements (19) mounted on the boiler tube. For Norcold 1200, see following section. 15. Slot in access door, and the tab that secures the heater access door. Carefully bend tab so that the housing can be squeezed to unlock the tab from the door so that the door can be removed. 16. The hinge for the door is a cutout in the door that fits into the boiler housing sheet metal. The top cutout is much longer than the bottom cutout seen in this photo. Once the tab is unlocked from the door, open the door to clear the heater elements (19). By pushing the door up, then sliding the lower cutout out of its lock position, the entire door may be removed. 17. Upon reinstalling of the heater element access door, use a blade type screw driver to push any insulation out of the hinged side of the door. If insulation is between the door and the boiler housing, this will make closing the door much harder. 9 of 12
18. ARP temperature sensor wire. Please wrap insulation around the ARP temperature sensor wire to protect the wire from the sharp sheet metal that can cut the wire upon closing the heater access door. 19. Cooling unit heaters. This example uses both 12VDC and 120VAC heater. Most operators will find that the 12VDC heaters do not provide good cooling within the refrigerated cabinet. In addition, the 12VDC heater can only be used when the vehicle engine is running to provide the power needed by this heater. Referencing Fig. 9 for the following discussion: Temperature Sensor Sensitivity Fig. 9 -- Install ARP Temperature Sensor The location at which the ARP temperature sensor is installed will make a great deal of difference regarding the sensitivity of the control. For example, if the sensor is mounted too close to the electrical heaters (19), the sensor will measure radiant heat from the electrical heater rather than the fluid temperature within the cooling unit boiler tube. The result is the reduction of sensitivity of the ARP control. The same problem is true of the flue tube, heat transfer from both the electric heaters and the gas flue tube will result in a slower response time for the ARP control. 10 of 12
Because each RV manufacturers' installs their refrigerator in a different manner, coupled with varying sizes of cooling unit access doors, the installer has to use the information in this document to determine the most practical temperature sensor location. This document merely provides guide lines which give the best results. 20. For ease of installation, either high temperature silicon grease, or spray silicon lubricant should be applied to the clip and the cooling unit boiler tube. This lube will help when positioning the sensor once snapped over the boiler tube. Also, for cooling units that have been in the field for a long time, rust on the boiler tube is an issue that makes it difficult to snap the clip (13) around the tube. 21. The ARP temperature sensor should be mounted as far up, and away from the heater elements as possible. The upper limit is usually determined by the heater element access door. The purpose of the ARP temperature senor is to measure the flow of weak solution within the boiler tube. The upper boundary for the installation of the temperature sensor is on the boiler tube adjacent to the upper absorber coil. Please see Fig. 2 and 6, #5 for lower absorber coil reference. The upper absorber coil is not possible to reach in most RV refrigerator installations. This is because the entire boiler housing needs to be removed to access the boiler tube adjacent to the upper absorber coil tube. For this reason, a good rule of thumb is to mount the temperature sensor as high on the boiler tube as possible for a particular make and model of refrigerator. Please note, on the Norcold N641 used for this example, the sensor is adjacent to the access door tab slot (15). 22. In Fig. 9, the location of the temperature sensor is for the convenience of the viewer. The red 'x' shows an alternant location for the sensor. The sensor can be rotated around the tube by about 30 degrees and still not be affected by the flue tube radiant heat transfer because the flue tube is directly behind the location of the sensor as seen in this photo. Please note that the flue tube is only welded to the cooling unit boiler tube in the area of the electric heaters. This weld is where the heat is transferred from the flue tube to the boiler. Please place insulation between the flue tube and the sensor to prevent radiant heat from reaching the sensor. Carefully Insulate RTD Probe Be sure to pack insulation all around the RTD so that there is no air space. For example, if there is an air pocket/space between the flue tube, or the heater elements, and the RTD, this air pocket will conduct heat directly from the heat source to the RTD. The result will be an unusually high reading. The RTD should only read the surface temperature of the boiler process tube, which in turn measures the temperature of the fluids within the tube. 23. Once that ARP temperature sensor has been located on the cooling unit boiler tube, fiber glass insulation is placed between the temperature sensor wire (18) and the boiler tube. In addition, insulate between the electric heaters (19) and wire (18). The ARP temperature sensor and wire/cable are rated for 250 C (482 F), but the flue tube and heaters can exceed this temperature. Most hardware stores carry fiberglass insulation for wrapping pipes. The insulation must be able to withstand high temperatures. 11 of 12
Fig. 10 -- Insulation of Boiler Housing Referencing Fig. 10 for the following discussion: 24. Once the temperature sensor (12 ) and wire (18) have been packed with insulation so that the temperature sensor is measuring the boiler tube alone, fill the remaining area within the boiler housing with insulation. Often, there are gaps in the insulation which allow heat to escape the boiler housing. The result is that your refrigerator louses efficiency due to heat losses. Being careful to insulate the boiler will yield many benefits in the future. Finally, we wrapped insulation around wire (18) in the location where boiler housing sheet metal and the heater access door would contact the temperature sensor wire. This is done to prevent the vibration associated with driving from chafing wire (18) where it passes through the boiler housing. Norcold 1200 Series The NHTSA document RCDNN-10E049-4150.pdf is referenced in the following discussion. The link to this document is: http://www-odi.nhtsa.dot.gov/acms/cs/jaxrs/download/doc/acm15568921/rcdnn-10e049-4150.pdf THIS SECTION WILL BE ADDED WHEN PHOTOS ARE PROVIDED 12 of 12